Process for the conversion of petroleum oil



Sept. 29, 1931. R. CROSS 1,825,337

PROCESS FOR THE CONVERSION OF PETROLEUM OIL Filed July 22, 1922 Patented Sept. 29, 1931 UNITED STATES PATENT OFFICE ROY CROSS, OF KANS AS CITY, MISSOURI, ASSIGNOR, BY MESNE ASSIGNMENTS, TO GASOLINE PRODUCTS COMPANY, OF WILMINGTON, DELAWARE, A CORPORATION OF DELAWARE Application filed July 22,

This invention relates to improvements in a process for the conversion of petroleum oils, and refers more particularly to a process in which relatively high boiling point oils are converted to oils of a low boiling point, while being maintained under a conversion temperature, and pressures suflicient to cause the cracking to take place in substantially liquid phase.

This invention is an improvement of a similar invention disclosed in Patent 1,437,229 issued November 28, 1922.

Among the salient objects of the invention are to provide a process in which the oil is preheated and introduced and circulated to a heating zone where it is raised to a conversion temperature, thence being directed to a relatively larger chamber in which a substantial body of the heated oil is permitted to collect and there undergo a molecular change while being maintained under pressure sufficient to prevent any substantial vaporization.

To provide a process in which the heated oil is collected in a zone of reaction where digestion takes place, this digestion or the assuming of an equilibrium consisting in a re-arrangement of the molecules forming a liquid product termed as synthetic crude which has an increased percentage of low boiling point 3 oils therein subsequent to the reaction. To provide a process in which the synthetic crude while in the heated condition and under substantial pressure is passed through a coil positioned in a tank or container through which the incoming oil is circulated and preheated. To provide an apparatus for carrying out this process, and in general to provide a process and apparatus of the character hereinafter referred to.

The single figure is a diagrammatic side elevational view of the apparatus. Referring to the drawing, the oil to be treated is introduced from any convenient source through the line 1, controlled by the valve 2, and is charged into the bottom of the tank 3 where it is preheated by a heating coil 4 positioned therein, the heating proclivities of which Will be hereinafter explained. The heated oil rising to the top of the tank is 50 drawn off through the line 5 and is charged PROCESS FOR THE CONVERSION OF PETROLEUM OIL 1922. Serial No. 576,659.

by means of the pump through the heating I coil 7 mounted in a furnace 8 which is preferably heated by means of gas burner 9. The oil after being raised to a conversion temperature in the heating zone is passed through the transfer line 10, controlled by valve 11 to the reaction chamber 12 which is fitted with a pyrometer 13 and a pressure gauge 14. The synthetic crude after being digested or after assuming an equilibrium which amounts primarily to a molecular or atomic re-arrangement producing a liquid oil product containing a substantial percentage of low boiling point oils, is withdrawn from the chamber 12 through the line 15 controlled by valve 16, and is directed through the preheating coil 4 which is coiled in the tank 3. The lower portion of the coil terminates in a transfer line 17, controlled by a valve 18, which passes the oil to a cooling coil 19 positioned in the Water cooler 20.

The oil or synthetic crude is passed after cooling, through the line 21 controlled by valve 22 to the gas separator 23 from which the incondensable gas is withdrawn through the line 24 controlled by the valve 25, and the liquid product drawn of]? through the line 26 controlled by the throttle valve 27, which permits the oil to flow into the storage tank 28.

By circulating the incoming oil about the preheating coil 4 through which is passed the heated oil withdrawn from the reacting chamber, advantage is taken of the heat contained in this oil, and due to the fact that it is in the liquid phase there is a more effective heat transfer than if the preheating coil contained a heated vapor.

For this reason it is of importance to have pressure on the ,oil in the preheating coil maintained sufiiciently high to prevent vaporization when the oil is Withdrawn from the high pressure reacting chamber 12..

In operation the oil is charged as explained, to the tank 3 where it surrounds the heating coil and is preheated by the heat conduction therefrom. A by-pass 29 controlled by a valve 30 is connected between the lines 1 and 5 in order that the oil circulated through the preheating tank may be controlled. The charging stock is withdrawn from the preheating tank and charged by means of the pump 6 through the heating coil where it is raised to temperatures ranging from 600 to 1000 F, and pressures of from 600 to 900 pounds. The oil is then passed to the digestion or reacting chamber Where substantially the same temperatures and pressures are maintained with perhaps a slight decrease in both temperature and pressure due to the inevitable heat losses and friction in transferring the liquid from one zone to the next. In the reaction chamber the oil is collected in a relatively large body and under pressures suflicient to prevent any substantial vaporization, nevertheless a conversion action takes place which consists in a molecular re-arrangement, producing an increased amount of lower boiling point hydrocarbons in the oil body which may be extracted by simple distillation.

The oil after digestion or conversion is withdrawn through the valve 16 and is directed through the preheating coil 4. The pressure of the oil upon the coil 4 is controlled by the valve18 at the discharge end of the coil.

The most eflicient preheating is obtained by maintaining suficient pressure upon the preheating coil to cause the oil to remain in a liquid state while passing through the preheating coil. As is well known, a preheating liquid is more effective than a vaporous medium.

The oil after passing from the preheating coil is directed to the cooling coil 19 at a reduced pressure, and is thence passed through a gas separator 23, the liquid synthetic crude drawn olf and collected in the storage tank 28, and the gas withdrawn through the line 24 to any desired collecting means notshown.

From the storage tank 28 synthetic crude may be redistilled to extract the low boiling point oils. The synthetic crude made in this process contains low boiling point oils which may be extracted in the same manner as the low boiling point oils from pressure distillates produced by distillation processes.

I claim as my invention:

1. A process of cracking hydrocarbons which comprises passing the hydrocarbons,

through heating tubes under cracking conditions of temperature and pressure, then passing the hydrocarbons along at a reduced rate of flow while maintaining them at cracking temperature and under such pressures as will prevent distillation, cooling the hydrocarbons in separate stages under substantially different pressures to a degree suflicient to prevent vaporization when they are discharged at an atmospheric pressure.

2. The process of cracking oil which comprises passing the oil through heating tubes under cracking conditions of temperature and pressure, then passing oil along at a reduced rate of flow while maintaining it at cracking temperatures and under such pressures as will prevent distillation, passing the oil through separate cooling stages, While maintaining positively graduated superatmospheric pressures thereon sufficient to prevent substantial vaporization, wherein the oil is cooled to a degree suflicient to prevent vaporization when it is released at atmospheric pressure.

3. A process of cracking oil comprising passing the oil through heating tubes under cracking conditions of temperature and pressure, passing the oil at reduced rate of flow through a stage maintained at cracking temperatures and under pressure conditions adapted to prevent distillation, passing the oil at an increased rate of flow through separate cooling stages maintained at substantially different pressures wherein the oil is cooled to a degree suflicient to prevent vaporization when it is released at atmospheric pressure.

4. A process of cracking hydrocarbons which comprises passing the hydrocarbons through heating tubes under cracking conditions of temperature and pressure, then passing the hydrocarbons along at a reduced rate of flow while maintaining them at cracking temperature and under such pressures as will prevent distillation, cooling the hydrocarbons in separate stages under substantially different pressures to a degree sufficient to prevent distillation when they are discharged at atmospheric pressure and subsequently separating gaseous and liquid products.

ROY CROSS. 

